The new head of the Environmental Protection Agency’s San Francisco headquarters vowed Friday to work diligently on environmental issues, including the clean up of toxic Superfund sites, a slate of work that he claims will keep him so busy it won’t matter that he still lives in Southern California. Mike Stoker, the 62-year-old Santa Barbara County attorney named last week as administrator of the EPA’s Pacific Southwest Region, was criticized by Sen. Dianne Feinstein, for what she said was his plan to oversee 702 San Francisco employees from a Los Angeles satellite office.